Blender on OS X Sierra 10.12.4 - Menus not working correctly
Ok, working with some other Mac software I found the following pattern to clean up stale bits that could be causing bad behavior.  

So I did the following rm -rf  ~/Library/Caches/Blender/*.  I assume I blew away a few customizations with this as weel.

I will just leave this here and hope it helps someone else.



The issue came back.  This time I unplugged all USB peripherals except my mouse and keyboard and the issue disappered.